A transmission of the kind described above is a reversing transmission as used especially in lift trucks, such as loaders. But it can also be the entry unit of a multi-speed reversing transmission as particularly used in constructions machines, such as wheel loaders, excavator loaders, etc.
Reversing transmissions of the kind mentioned have, in general, an input shaft and, as a rule, several countershafts. Clutches (so-called direction and gearshift clutches) having idler gearwheels which can optionally be non-rotatably connected with the shafts for shifting a gear and direction, are situated upon said countershafts. The power take-off is effected by a driven gear system. The number of fixed gearwheels depends on the number of gears of the transmission.
Powershift reversing transmissions of a countershaft design stand out by a series of advantages. Such transmissions are consequently used in several industrial vehicles. Said transmissions must be compact in construction and comfortable for gearshifts. For this purpose, the hydraulically actuatable clutches are mainly shifted by modulation of the actuating pressure in a manner such that a controlled load take-up results. In certain vehicles, for example, in lift trucks such as fork lift trucks or the like, other operating conditions are of special importance together with the reversing operation. To said conditions mainly belong starting off, inching and raking.